Symmetrical tip acute catheter

ABSTRACT

A medical catheter assembly includes a catheter tip coupled to a distal end of an elongate catheter member and is symmetric about a plane defined by a septum of the elongate catheter member. The catheter tip defines first and second lumens, and the catheter tip defines first and second openings in the distal portion of the catheter tip. Each opening of the catheter tip is defined by a respective side surface of the catheter tip. Each opening is in fluid communication with a respective one of the first and second lumens of the catheter tip and with a respective one of a pair of lumens defined by the elongate catheter member. The distance between upper and lower surfaces of the catheter tip decreases from a distal end of the proximal portion toward a closed distal end of the catheter tip.

This application is a divisional of U.S. application Ser. No.14/852,934, which was filed on Sep. 14, 2015, is entitled, “SYMMETRICALTIP ACUTE CATHETER,” and is a divisional of U.S. patent application Ser.No. 13/629,915, which was filed on Sep. 28, 2012 and is entitled,“SYMMETRICAL TIP ACUTE CATHETER.” The entire content of U.S. applicationSer. No. 14/852,934 and U.S. patent application Ser. No. 13/629,915 isincorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to a catheter assembly, and, inparticular, to a symmetrical tip acute catheter.

BACKGROUND

Catheters are flexible medical instruments intended for the withdrawaland introduction of fluids to and from body cavities, ducts and vessels.Catheters have particular application in hemodialysis procedures, inwhich blood is withdrawn from a blood vessel for treatment andsubsequently returned to the blood vessel for circulation. Hemodialysiscatheters can include multiple lumens, such as dual lumen or triplelumen catheters, which permit bi-directional fluid flow within thecatheter whereby one lumen, the arterial lumen, is dedicated forwithdrawal of blood from a vessel and the other lumen, the venous lumen,is dedicated for returning purified blood to the vessel. During somehemodialysis procedures, a multiple lumen catheter is inserted into abody, and blood is withdrawn through the arterial lumen of the catheter.The withdrawn blood is directed to a hemodialysis unit which dialyzes,or purifies, the blood to remove waste and toxins. Thereafter, thedialyzed blood is returned to the patient through the venous lumen ofthe catheter.

Generally, hemodialysis catheters are categorized as either chronic oracute in nature. Chronic catheters typically remain in place forextended periods of time, and may be implanted via surgical dissection.Acute catheters, by comparison, are designed to be placed in a patientunder emergent circumstances in which speed of placement is desirable.Acute catheters typically remain in place for only a few days. As such,acute catheters are often more rigid than chronic catheters, given theurgency of placement.

In hemodialysis catheters, recirculation can occur when purified bloodexiting the venous lumen of the catheter is withdrawn directly into thearterial lumen such that purified blood is returned to the dialyzer. Assuch, recirculation increases the time required to complete thehemodialysis procedure.

SUMMARY

The present disclosure is directed to further improvements inhemodialysis catheters and systems used therewith. A catheter assemblyincludes an elongate catheter member, and a catheter tip. The elongatecatheter member includes a septum defining at least a portion of each ofa pair of internal lumens. The catheter tip is coupled to a distal endof the elongate catheter member and is symmetric about a plane definedby the septum. The catheter tip includes a distal portion and a proximalportion, an upper surface, a lower surface, and side surfaces betweenthe upper and lower surfaces, the distal portion including a closeddistal end. The catheter tip defines first and second lumens and firstand second openings in the distal portion of the catheter tip. Eachopening is defined by a respective side surface of the catheter tip.Each opening is in fluid communication with a respective one of thefirst and second lumens of the catheter tip and with a respective one ofthe first and second lumens of the elongate catheter member. Thedistance between the upper and lower surfaces of the catheter tipdecreases from a distal end of the proximal end portion toward theclosed distal end. The first and second openings are diametricallyopposed to one another and may be laser-cut or otherwise formed to havecontoured edges to reduce the likelihood of thrombus formation.

The first and second passages of the catheter tip are in fluidcommunication with a respective one of the pair of internal lumens ofthe elongate catheter member such that fluids may pass between theelongate catheter member, the catheter tip, and the first and secondopening so that the catheter member is in fluid communication with anoutside environment such as an internal body cavity. The pair ofinternal lumens may be configured for opposing bi-directional fluidflow, as in the case of hemodialysis procedures. In embodiments, one ormore connecting members may be disposed between the elongate cathetermember and the catheter tip, and the one or more connecting members maydefine channels to facilitate communication between the elongatecatheter member and the catheter tip. Distal ends of the connectingmembers may be disposed adjacent the proximal ends of the first andsecond side openings such that fluids exit the connecting members uponreaching the proximal ends of the first and second side openings.

In embodiments, the distance between the upper and lower surfaces alongthe proximal portion increases in the distal direction adjacent thedistal portion. In another embodiment, the proximal portion of thecatheter tip is defined by a curved spheroid region. In still anotherembodiment, the first and second openings are each an elongate oval.

In a further embodiment of the present disclosure, the elongate cathetermember defines a longitudinal axis and the first and second sideopenings are spaced a distance along the longitudinal axis from thedistal end of the catheter tip. In another embodiment of the presentdisclosure, the first and second internal lumens are semicircular incross-sectional shape.

In still another embodiment, the elongate catheter member and thecatheter tip are coupled by at least one connecting member extendingtherebetween. The at least one connecting member defines a channel influid communication with the elongate catheter member and the cathetertip. The at least one connecting member may include a proximal end and adistal end, and the distal end of the connecting member is adjacent oneof the first and second side openings. The first and second sideopenings each have a contoured perimeter.

In a further embodiment of the present disclosure, a medical catheterincludes an elongate tubular member defining a pair of lumens and alongitudinal axis. A pair of diametrically opposed side openings influid communication with the respective pair of lumens. Each sideopening has a proximal end and a distal end, and each side opening hasan elongated substantially z-shaped configuration including arectangular central portion defining a transverse axis and triangularproximally and distally extending portions. The triangular proximallyextending portion defines an apex at the proximal end of the sideopening and the triangular distally extending portion defines an apex atthe distal end of the side opening. The transverse axis of therectangular central portion defines an acute angle with the longitudinalaxis of the elongate tubular member. The acute angle can be betweenabout fifteen and about seventy-five degrees. In some embodiments, theelongate tubular member includes a septum defining at least a portion ofeach of the pair of lumens. The septum extends parallel to thelongitudinal axis, and the elongate tubular member is symmetrical abouta plane defined by the septum. In certain embodiments, the pair of sideopenings each have contoured edges. In some embodiments, the proximaland distal ends of each of the side openings are rounded.

Other aspects, features, and advantages will be apparent from thedescription and drawings, and from the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a distal portion of a medical catheterincluding an elongate catheter member and a tip.

FIG. 2 is a cross-sectional view of the medical catheter of FIG. 1,taken along section line 2-2 of FIG. 1.

FIG. 3A is a perspective view of the tip of the catheter of FIG. 1including a pair of side openings.

FIG. 3B is a side view of the catheter tip of FIG. 3A.

FIG. 3C is a top view of the catheter tip of FIG. 3A.

FIG. 4A is a perspective view of a catheter tip which includes aproximal portion having a changing diameter from the proximal portion tothe distal portion.

FIG. 4B is a side view of the catheter tip of FIG. 4A.

FIG. 4C is a top view of the catheter tip of FIG. 4A.

FIG. 5A is a perspective view of a catheter tip having a proximalportion with a curved spheroid region.

FIG. 5B is a side view of the catheter tip of FIG. 5A.

FIG. 5C is a top view of the catheter tip of FIG. 5A.

FIG. 6A is a perspective view of an alternate embodiment of a cathetertip having diametrically opposed top and bottom planar surfaces and aproximal portion having top and bottom walls which diverge outwardly asthe proximal portion approaches a distal portion of the catheter tip.

FIG. 6B is a side view of the catheter tip of FIG. 6A.

FIG. 6C is a top view of the catheter tip of FIG. 6A.

FIG. 7A is a perspective view of a catheter tip including diametricallyopposed planar top and bottom surfaces and having side openingsextending through the distal end of the catheter tip.

FIG. 7B is a side view of the catheter tip of FIG. 7A.

FIG. 7C is a top view of the catheter tip of FIG. 7A.

FIG. 8A is a perspective view of a catheter assembly including anelongate catheter member having a pair axially opposed and offsettapered slots.

FIG. 8B is a side view of the catheter assembly of FIG. 8A.

FIG. 8C is a top view of the catheter assembly of FIG. 8A.

FIG. 9A is a perspective view of a catheter assembly including sideopenings having rounded ends.

FIG. 9B is a side view of the catheter assembly of FIG. 9A.

FIG. 9C is a top view of the catheter assembly of FIG. 9A.

FIG. 10A is a perspective view of a catheter assembly having a catheterbody with a pair of diametrically opposed side openings, each shaped asa tapered slot with rounded ends.

FIG. 10B is a side view of the catheter assembly of FIG. 10A.

FIG. 10C is a top view of the catheter assembly of FIG. 10A.

FIG. 11A is a perspective view of a catheter assembly having a catheterbody with a pair of diametrically opposed side openings, each having atruncated oval shape with a flat distal wall.

FIG. 11B is a side view of the catheter assembly of FIG. 11A.

FIG. 11C is a top view of the catheter assembly of FIG. 11A.

FIG. 12A is a perspective view of a catheter assembly having a catheterbody with a pair of diametrically opposed side openings each having ashape defined by a circular distal portion intersecting a smallercircular proximal portion.

FIG. 12B is a side view of the catheter assembly of FIG. 12A.

FIG. 12C is a top view of the catheter assembly of FIG. 12A.

FIG. 13A is a perspective view of a catheter assembly having a catheterbody with a pair of diametrically opposed side openings each having anL-shape including rectangular slots intersecting in transverse relation.

FIG. 13B is a side view of the catheter assembly of FIG. 13A.

FIG. 13C is a top view of the catheter assembly of FIG. 13A.

FIG. 14A is a perspective view of a catheter assembly having a catheterbody with a pair of diametrically opposed side openings having a shapedefined by a circular distal portion intersecting a circular proximalportion.

FIG. 14B is a side view of the catheter assembly of FIG. 14A.

FIG. 14C is a top view of the catheter assembly of FIG. 14A.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Embodiments of the presently disclosed catheters are discussed in termsof medical catheters for the administration of fluids and, moreparticularly, in terms of hemodialysis catheters. However, it isenvisioned that the present disclosure may be employed with a range ofcatheter applications including surgical, diagnostic and relatedtreatments of diseases and body ailments, of a subject. It is furtherenvisioned that the principles relating to the presently disclosedcatheters include, for example, hemodialysis, cardiac, abdominal,urinary, intestinal, in chronic and/or acute applications.

In the discussion that follows, the term “proximal” will refer to theportion of a structure closer to an operator, while the term “distal” orwill refer to the portion further from the operator. As used herein, theterm “subject” refers to a human patient or other animal. The term“operator” refers to a doctor, nurse or other care provider and mayinclude support personnel.

Referring now to FIGS. 1-2, a catheter 10 includes a catheter body 20and a catheter tip 40. The catheter body 20 defines a longitudinal axis“A” and may have a substantially circular cross-section. The catheterbody 20 defines a pair of lumens 22, 23 extending the length of catheter10. Alternately, the catheter 20 may define a third lumen for receivinga guidewire or the like. The lumens 22, 23 may include oblong,kidney-shaped, and/or D-shaped cross-sectional configurations. A septum24 defined by the catheter body 20 is disposed between the adjacentlumens 22, 23 and can define at least a portion of each lumen 22, 23. Insome embodiments, the catheter tip 40 has a substantially frusto-conicalprofile. The frusto-conical shape may aid in the insertion of thecatheter 10, for example, in time-sensitive circumstances in which acutecatheters are utilized.

The components of the catheter 10 may be fabricated from materialssuitable for medical applications, such as, for example, polymers,silicone and/or polyurethane. The catheter body 20 is flexible and maybe formed by injection molding or extrusion. The catheter body 20 mayhave a preformed bend in its normal condition to facilitate conformingto an internal body cavity or vessel in which the catheter body 20 is tobe positioned. Alternatively, catheter body 20 may be substantiallystraight.

The catheter tip 40 may be fabricated from material suitable for medicalapplication, including, for example, polymers, silicone, and/orpolyurethane. In addition, the catheter tip 40 fabricated from the samematerial or a different material than catheter body 20. In someembodiments, catheter tip 40 is formed separately from catheter body 20and is secured to a distal end portion of the catheter body 20. Incertain embodiments, the catheter tip 40 is integrally or monolithicallyformed with the catheter body 20.

The catheter tip 40 includes a partition 44. The catheter tip 40 and thepartition 44 define the lumens 42. An outer surface 47 of catheter tip40 is tapered distally and approaches a closed, distal end 46 to aidinsertion of the catheter 10. While the distal end 46 is shown as havinga rounded, blunt profile, other shapes and profiles of the distal end 46are possible. When the catheter body 20 and the catheter tip 40 areassembled, the lumens 42 of tip 40 are in fluid communication with andare aligned with the lumens 22, 23 of the catheter body 20. Similarly,the septum 24 and the partition 44 are aligned such that lumens 22, 23and the respective lumens 42 define substantially parallel and separatepathways parallel to the longitudinal axis A along the catheter body 20.At least a distal portion of the septum 24 and a proximal portion of thepartition 44 have substantially similar dimensions to provide a smoothtransition between the catheter body 20 and the catheter tip 40.

The catheter tip 40 may include a pair of proximally extendingconnecting members 48 that are insertable into lumens 22, 23. Theconnecting members 48 are spaced to receive septum 24 and definechannels 50. The channels 50 are in fluid communication with the lumens22, 23 of the catheter body 20 when the catheter body 20 and thecatheter tip 40 are assembled. The connecting members 48 may engage thelumens 22, 23 with an interference or frictional fit, forming asubstantially fluid tight seal with lumens 22, 23. Alternatively oradditionally, the connecting members 48 may be secured within withlumens 22, 23 using chemical adhesives or mechanical coupling, such asby welding.

Referring now to FIGS. 3A-3C, a pair of side openings 52 is defined inthe outer surface 47 of the catheter tip 40. The side openings 52 aresubstantially elongated, oval shaped slots that extend along cathetertip 40 and are symmetrical about the longitudinal axis A. The sideopenings 52 allow fluid streams F, F′ to travel between an environment,such as an internal body cavity, and the internal lumens 42. The sideopenings 52 may have contoured edges formed, for example, by lasercutting, molding with catheter tip 40, and/or otherwise smoothed tominimize flow disruption and thrombus formation.

In a hemodialysis application, a proximal end portion of catheter body20 (FIG. 1) is connected to a dialyzer (not shown) such that blood iswithdrawn from a body vessel through one lumen 22 (FIG. 2), the arteriallumen, of the catheter body 20 via the respective side opening 52 of thecatheter tip 40 and delivered to a dialyzer for purification. Thepurified blood is then returned to the body vessel through the secondlumen 23, the venous lumen, of the catheter body 20 via the other sideopening 52 of the catheter tip 40. Because of the symmetricalconfiguration of the catheter body 20, and the catheter tip 40 and thelumens 42, either lumen 22, 23 may serve as the arterial lumen or thevenous lumen. Because of the configuration of the catheter tip 40, theblood flow stream F into the side opening 52 communicating with thearterial lumen 22 and the blood flow stream F′ exiting the side opening52 communicating with the venous lumen 23 are separated such that thedegree of fluid recirculation is minimized.

The symmetrical nature of the catheter tip 40, the diametrically opposedpositioning of side openings 52 along the tip 40, and the elongatedshape of side openings 52 enables the spacing between the fluid streamF′ exiting venous lumen 23 and the fluid stream F entering arteriallumen 22 to be maximized, which minimizes the degree of recirculation ofpurified blood between the venous lumen 23 and the arterial lumen 22 ofthe catheter 10 (FIG. 1). Specifically, blood enters proximally throughthe side openings 52 and exits distally through the side openings 52.The outer surface 47 and the distal end 46 of the catheter tip 40provide spacing that substantially minimizes the fluid stream F′ exitingthe venous lumen 23 from migrating toward the fluid stream F enteringthe arterial lumen 22, which can also minimize the degree of fluidrecirculation.

Referring now to FIGS. 4A-4C, a catheter tip 140 includes a proximalportion 141 and a distal portion 143. The distal portion 143 of thecatheter tip 140 gradually tapers towards a closed distal end 146, whichmay have a blunt or a traumatic shape. The proximal portion 141increases in diameter in a direction toward the distal portion 143. Theincrease in diameter along proximal portion 141 provides a radiallyexpanding surface proximal to side openings 152. This radially expandingsurface can direct fluid stream F′ away from the side openings 152. Theside openings 152 can be similar in configuration to side openings 52and define an elongated oval configuration formed along the sides of theouter surface 147 of catheter tip 140. Because of the configuration ofthe catheter tip 140, the blood flow stream F into the side opening 152communicating with an arterial lumen and the blood flow stream F′exiting the side opening 152 communicating with a venous lumen areseparated such that the degree of fluid recirculation is minimized.

Referring now to FIGS. 5A-5C, a catheter tip 240 includes a proximalportion 241 and a distal portion 243. The distal portion 243 has asubstantially tapered profile that gradually tapers towards a closeddistal end 246. The catheter tip 240 defines a pair of side openings 252disposed along opposed sides of the outer surface 247 of the cathetertip 240. The proximal portion 241 of the catheter tip 240 is a curvedspheroid region adjacent the distal portion 243. The curved spheroidregion of the proximal portion 241 provides a radially expanding surfaceproximal to the side openings 252 that directs fluid stream F′ away fromside openings 252 to minimize recirculation of fluid stream F′ in themanner discussed above with respect to catheter tip 140.

Referring now to FIGS. 6A-6C, a catheter tip 340 includes diametricallyopposed planar surfaces 354, a proximal portion 341 and a distal portion343. Lateral surfaces 360 of proximal portion 341 diverge outwardly in adirection toward distal portion 343. Each planar surface 354 extends thelength of the catheter tip 340 and converges inwardly approaching ablunt distal end 346. Side surfaces 362 of the distal portion 343 taperinwardly in a direction approaching the distal end 346. Side openings352 are similar to openings 52, 152 and 252 discussed above. Each sideopening 352 is positioned along a respective side surface 362. Theplanar surfaces 354 direct fluid stream F′ away from side openings 352by providing a path of least resistance for fluid stream F′ to flowtoward distal end 346. The lateral surfaces 360 of the proximal portion341 also direct fluid outwardly of side openings 352.

Referring now to FIGS. 7A-7C, a catheter tip 440 defines a pair ofdistally positioned, diametrically opposed side openings 452 along theouter surface of a catheter tip 440. The side openings 452 extendthrough a portion of a distal end 446 of the catheter tip 440. The sideopenings 452 are in fluid communication with internal lumens 442 ofcatheter tip 440. The catheter tip 440 functions in a manner similar tothat described above with respect to catheter tip 340 (FIGS. 6A-6C).

Referring now to FIGS. 8A-8C, a catheter 510 includes an elongated body520 and a catheter tip 540 supported at the distal end of the elongatedbody 520. The elongated body 520 defines first and second lumens (notshown) which extend from a proximal end of the catheter 510 toward thedistal end of the catheter 510. In some embodiments, the catheter tip540 is substantially conical and tapers inwardly in the distal directionto define a blunt or a traumatic end.

The catheter body 520 defines first and second side openings 526diametrically opposed to one another along the length of body 520. Eachside opening 526 is in fluid communication with a respective one of thefirst and second lumens. Each side opening 526 has an elongated Z-shapedconfiguration including a rectangular or rhombus-shaped central portion527 a and triangular proximal and distal portions 527 b and 527 c. Theapex of the triangular portion 527 b is at the proximal end of thetriangular portion 527 b and the apex of the triangular portion 527 c isat the distal end of the triangular portion 527 c. In some embodiments,the rectangular portion 527 a defines a transverse axis T (FIG. 8B)which defines an acute angle θ with a longitudinal axis B defined by thecatheter body 520. For example, the angle θ can be between about fifteendegrees and about seventy-five degrees. In certain embodiments,sidewalls 529 defining a portion of rectangular portion 527 a andtriangular portions 527 b and 527 c are substantially parallel to alongitudinal axis B defined by catheter body 520.

As discussed above, the side openings 526 are symmetrically positionedon opposite sides of the catheter body 520 and each of the side openings526 communicates with a respective lumen of the catheter 510. The sideopenings 526 facilitate separation of the fluid flow stream F into thearterial lumen of the catheter 510 and the fluid flow stream F′ exitingthe venous lumen of the catheter 510. More specifically, because of theconfiguration of the side openings 526, blood flow has a tendency toflow into a proximal end of the side opening communicating with thearterial lumen of the catheter body 520 and exit the distal end of theside opening 526 communicating with the venous lumen of the catheterbody 520. Because of this, the fluid streams F and F′ to and from thecatheter 510 are spaced to minimize the degree of recirculation withinthe catheter body 520.

Referring to FIGS. 9A-9C, a catheter 610 includes a body 620 definingside openings 626 that have rounded proximal and distal ends 627. Theingress and egress points for fluid flow streams F, F′ through arterialand venous lumens (not shown), respectively, are axially spaced apart asdescribed above. Thus, fluid stream F entering the arterial lumen andfluid stream F′ exiting the venous lumen are circumferentially andaxially spaced apart, to minimize the degree of recirculation. Ascompared to sharp edges, the rounded edges 627 of side openings 626reduce shear stresses on the blood flow to reduce the likelihood ofthrombus formation.

Referring to FIGS. 10A-10C, a catheter 710 defines a pair ofdiametrically opposed side openings 726, each side opening having aproximal end 727 and a distal end 728. The side openings 726 have asubstantially teardrop-shaped profile with rounded ends. The taper ofthe teardrop shape of each side opening 726 tapers proximally from theproximal end 727 to the distal end 728, with the proximal end 727 havinga smaller radius of curvature than the distal end 728. Fluid stream Fenters an arterial lumen at the proximal end 727. Fluid stream of F′exits a venous lumen at the distal end 728. Accordingly, proximal anddistal flow of fluid streams F, F′ through respective lumens are bothaxially and circumferentially spaced to minimize recirculation.

Referring to FIGS. 11A-11C, a catheter 810 defines a pair ofdiametrically opposed side openings 826. Each side opening 826 has aproximal end 827 and a distal end 828 and an elongated, truncated ovalshape. The distal end 828 of each side opening 826 has a generally flator planar shape. Each side opening 826 tapers proximally and narrowstoward the respective proximal end 827, which has a curved shape. Fluidstream F enters an arterial lumen at the proximal end 827 and fluidstream F′ exits a venous lumen at the distal end 828. Accordingly,proximal and distal flow of fluid streams F, F′ through respectivelumens are both axially and circumferentially spaced from one another tominimize recirculation.

Referring to FIGS. 12A-12C, a catheter 910 defines a pair ofdiametrically opposed side openings 926. Each side opening 926 has aproximal portion 927, a distal portion 928, and a substantiallypear-shaped profile. The distal portions 928 of each side opening 926 isarcuate and has a first diameter “A1”, and the proximal portion 927 ofeach side opening 926 is arcuate and has a second diameter “A2” that issmaller than diameter A1. The respective proximal portions 927 anddistal portions 928 intersect along a transverse axis T′ of catheter910. Fluid stream F enters an arterial lumen at the proximal portion927, and fluid stream F′ exits a venous lumen at the distal portion 928.Accordingly, proximal and distal flow of fluid streams F, F′ throughrespective lumens are both axially and circumferentially spaced relativeto one another to minimize recirculation.

Referring to FIGS. 13A-13C, a catheter 1010 defines a pair ofdiametrically opposed side openings 1026. Each side opening 1026 has aproximal portion 1027 and a distal portion 1028 and has a substantiallyL-shaped profile. The distal portion 1028 of each side opening 1026extends across a portion of the surface of the catheter 1010 intransverse relation to a longitudinal axis A′ of catheter 1010. Theproximal portion 1027 of each side opening 1026 extends along a portionof the surface of the catheter 1010 parallel to the longitudinal axis A′and intersects a respective distal portion 1028. Fluid stream F entersan arterial lumen at the proximal portion 1027 and exits a venous lumenat the distal portion 1028. Accordingly, proximal and distal flow offluid streams F, F′ through respective lumens are both axially andcircumferentially spaced from one another.

Referring to FIGS. 14A-14C, a catheter 1110 defines a pair ofdiametrically opposed side openings 1126. Each side opening 1126 has aproximal portion 1127, a distal portion 1128, and a substantially figureeight-shaped profile. The proximal portion 1127 and distal portion 1128of each respective side opening 1126 each have a shape defined by anarcuate distal portion intersecting an arcuate proximal portion, and aresymmetric about a transverse axis B″ of the catheter 1110. Fluid streamF enters an arterial lumen at the proximal portion 1127, and fluidstream F′ exits a venous lumen at the distal portion 1128. Accordingly,proximal and distal flow of fluid streams F, F′ through respectivelumens are both axially and circumferentially spaced from one another tominimize recirculation.

Although the illustrative embodiments of the present disclosure havebeen described herein with reference to the accompanying drawings, it isto be understood that the disclosure is not limited to those preciseembodiments, and that various other changes and modifications may beeffected therein by one skilled in the art without departing from thescope or spirit of the disclosure.

What is claimed is:
 1. A medical catheter comprising: an elongatecatheter body defining a pair of lumens, a longitudinal axis, and a pairof diametrically opposed side openings, each side opening in fluidcommunication with a respective lumen of the pair of lumens, wherein thelumens of the pair of lumens define separate pathways parallel to thelongitudinal axis, wherein each side opening has a proximal end, adistal end, a first side, and a second side, wherein the first andsecond sides extend from the respective proximal end to the respectivedistal end to define a shape that tapers proximally over an entirelength of the side opening between the distal end and the respectiveproximal end, wherein the first and second sides are nonparallel to thelongitudinal axis, and wherein the distal end of each side opening isrounded and is proximal to a distal end of the elongate catheter body,wherein the elongate catheter body includes a distal portion having aclosed distal end, and wherein the elongate catheter body comprises aseptum defining at least a portion of each lumen of the pair of lumens,the septum extending parallel to the longitudinal axis, wherein theelongate catheter body is symmetrical about a plane defined by theseptum.
 2. The medical catheter of claim 1, wherein the shape is asubstantially teardrop shape that tapers between the proximal end andthe respective distal end.
 3. The medical catheter of claim 2, whereinthe proximal end of each of the side openings is rounded.
 4. The medicalcatheter of claim 3, wherein the proximal end of each side opening has asmaller radius of curvature than the distal end of the respective sideopening.
 5. A medical catheter comprising: an elongate catheter bodydefining a pair of lumens, a longitudinal axis, and a pair ofdiametrically opposed side openings, each side opening in fluidcommunication with a respective lumen of the pair of lumens, wherein thelumens of the pair of lumens define separate pathways parallel to thelongitudinal axis, wherein each side opening has a proximal end and adistal end, and a shape that tapers proximally, each side openingdefining a respective opening axis that extends through the respectiveproximal end and the respective distal end, and is parallel to thelongitudinal axis, wherein the distal end of each side opening isproximal to a distal end of the elongate catheter body and has a flatshape, and wherein the shape of each side opening includes two sidesthat converge inward towards the opening axis, the two sides of the sideopening being nonparallel to the longitudinal axis and being positionedbetween the proximal end and the distal end of the side opening, andwherein the proximal end of each side opening is rounded, wherein theelongate catheter body includes a distal portion having a closed distalend, and wherein the pair of lumens comprises a first lumen and a secondlumen, wherein the first lumen is configured to be used to introducefluid into the patient while the second lumen is used to withdraw fluidfrom the patient.
 6. A medical catheter comprising: an elongate catheterbody defining a pair of lumens, a longitudinal axis, a transverse axisorthogonal to the longitudinal axis, and a pair of diametrically opposedside openings, each side opening in fluid communication with arespective lumen of the pair of lumens, wherein the lumens of the pairof lumens define separate pathways parallel to the longitudinal axis,wherein when the catheter body is straight, each side opening has asubstantially figure-eight shape comprising an arcuate distal portionhaving a first diameter and an arcuate proximal portion having a seconddiameter, the arcuate proximal and distal portions intersecting alongthe transverse axis between the arcuate proximal and distal portions,wherein the elongate catheter body includes a distal portion having aclosed distal end, and wherein the pair of lumens comprises a firstlumen and a second lumen, and wherein the first lumen is configured tobe used to introduce fluid into the patient while the second lumen isused to withdraw fluid from the patient.
 7. The medical catheter ofclaim 6, wherein the second diameter is smaller than the first diameter.8. The medical catheter of claim 6, wherein the first diameter issubstantially equal to the second diameter.
 9. The medical catheter ofclaim 6, wherein each side opening is symmetric about the transverseaxis of the elongate catheter body.
 10. A medical catheter comprising:an elongate catheter body defining a pair of lumens, a longitudinalaxis, a closed distal end, and a pair of diametrically opposed sideopenings, each side opening in fluid communication with a respectivelumen of the pair of lumens, wherein each side opening is L-shaped andcomprises a distal portion extending in a transverse relation to thelongitudinal axis and a proximal portion extending parallel to thelongitudinal axis, the proximal portion intersecting the distal portion,wherein a proximal-most end of the proximal portion has a generally flatshape, and wherein the lumens of the pair of lumens define separatepathways parallel to the longitudinal axis, wherein the pair of lumenscomprises a first lumen and a second lumen, and wherein the first lumenis configured to be used to introduce fluid into the patient while thesecond lumen is used to withdraw fluid from the patient.
 11. The medicalcatheter of claim 6, wherein each side opening is substantiallysymmetrical with respect to the longitudinal axis.
 12. The medicalcatheter of claim 10, wherein a distal-most end of the distal portionhas a generally flat shape, and wherein the proximal-most end issubstantially parallel to the distal-most end.
 13. The medical catheterof claim 1, wherein the pair of lumens extend a length of the medicalcatheter.
 14. The medical catheter of claim 1, wherein the pair oflumens comprises a first lumen and a second lumen, and wherein the firstlumen is configured to be used to introduce fluid into the patient whilethe second lumen is used to withdraw fluid from the patient.
 15. Themedical catheter of claim 14, wherein the second lumen is configured tobe used to introduce fluid into the patient while the first lumen isused to withdraw fluid from the patient.